


SkeleFrisk: Demons' Revenge

by HufflepuffKat



Series: SkeleFrisk [2]
Category: Undertale (Video Game)
Genre: Aftermath, Alternate Universe - Angels & Demons, Alternate Universe - Canon Divergence, Big Brother Papyrus, Big Brother Sans, Demons, Don't mess with Papyrus or you will get a BAD time, Falmercia is still learning about emotions, Falmercia's past comes back to bite her, Gen, I don't think there is a single person in this fic that wouldn't kill to protect Papyrus, Innocent Papyrus, Papyrus Knows More Than He Lets On, Protective Sans, Sans is a scientist, School, Sequel, Skeleton Frisk, Skeletons, Soul Magic, Souls, Stalking, University, Worried Papyrus, because of this her character seem a little inconsistant, but it is because she masks her true feelings a lot, skelebros, villain reform
Language: English
Status: In-Progress
Published: 2018-05-05
Updated: 2018-09-06
Packaged: 2019-05-02 12:52:12
Rating: Teen And Up Audiences
Warnings: Graphic Depictions Of Violence
Chapters: 6
Words: 9,490
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/14545170
Author URL: https://archiveofourown.org/users/HufflepuffKat/pseuds/HufflepuffKat
Summary: Life goes on, and the world does with it. Falmercia struggles to keep her past behind her as past enemies stalk her and subtly mess with her.Sans just wants to keep his family safe, but Falmercia might be their only hope to keep them that way after things are far too late.Can they put their own past behind them and trust Falmercia to help them? Or will they need to find another way. It would be a shame if they did, since Falmercia always seems to have a plan for everything.





	1. Chapter 1

Toriel knocked on Falmercia's door. She could hear a loud sigh from the other side.

"Come in, Tor." It hadn't taken long for Falmercia to get tired of calling Toriel by her titles and even her name, and had settled for the shortest nickname the demon could think of.

Toriel didn't mind, although the tales that she had heard from the others didn't paint Falmercia in a good light, the demon reminded her of a typical tired college student; only doing the absolute minimum effort to survive because they had burned out after the first semester.

Not exactly the most sinister image. Besides, monster kind  _did_  owe the demon a lot all things considered. Even if the demon only did what she did for self-betterment.

Toriel entered the room and immediately squinted in an attempt to see through the darkness. Falmercia's room didn't have much in it; no desks, chairs, dressers and no lights, only a single queen-sized bed.

The bed itself was a mess of blankets and pillows, and Toriel had no doubt that it had never been made. When Toriel approached the bed, Falmercia drowsily popped her head out from one of the blankets.

"What?" She asked, obviously annoyed that Toriel had disturbed her.

Toriel braced herself, "I would appreciate if you reconsider my request that you-"

"I'm not going to teach soul magic for you. A job is too much work." Falmercia cut her off. This wasn't anywhere near the first time that Toriel had made this request, and this time she was ready and had a plan. This time, she was not going to take 'no' for an answer.

"I have spoken with the school, you would only have to teach a class for one hour at a time, three times a week." Toriel said calmly. Falmercia groaned. " _and_  as I have told you before, you would get paid rather well."

Falmercia rolled her eyes, "And as I have told  _you_  before, demons don't value money. I'd have no use for it, even with this 'online shopping', spending it is too much effort."

Toriel felt a smirk creeping on her face, time to use her trump card, "I heard from Papyrus that you get bored on occasion." Falmercia froze, and her eyes widened. Toriel paused to see if Falmercia would try to deny it, but she only lowered her head.

"Stupid broken chain." She muttered. Toriel raised an eyebrow, what was she talking about? Oh well.

She continued, "If you take the job, I will install a new television in your room for you," That got Falmercia's attention, "And I'll pay for MTTflix for you as long as you keep the job."

"Hey mortals, I'm here because I'm contractually obliged to teach this class Soul magic as part of this school's new magic curriculum." Falmercia said walking into her classroom. 'Damn Toriel' she thought, before scanning the classroom.

As she expected, Gaster had taken a seat closer to the front, Sans sitting next to him. She figured the third monster scientist mustn't be here because the humans had insisted that at least one person was manning the CORE at a time, under the false belief that it was unstable like their own nuclear power-plants. She figured that Sans and Gaster would attempt to teach Alphys what they had learnt themselves as time goes on and she inwardly groaned.

'That's going to be a nightmare of a mess that  _I_  will have to clean up.'

Falmercia was slightly surprized to see a few other monsters scattered amongst the crowd, the only one she recognised being Madjick. The rest of her students were humans of varying ages from some being very young to others being older – for humans, that was.

"Let me introduce myself. I'm Falmercia, I'm a demon; more specifically, a sloth demon. I am the embodiment of the sin of false mercy; which is a fancy way of saying 'cheating'. So, if any of you in the future want to try and cheat in my class; go ahead, knock yourselves out, I won't penalize you for it, you're the ones that supposedly want to learn here." Falmercia felt a small amount of achievement when she saw the shocked looks on faces of the students that hadn't met her before.

"But miss! That's against the school's policy!" One of the younger students cried.

Falmercia smirked, "You'll find that my class doesn't follow a lot of the school's policies. There has never been an accurate Soul magic class in the history of mortals before, and I'm the only one qualified that's willing to teach it, which basically means one thing; my class, my rules."

Students started exchanging glances and Falmercia continued, "Unlike the rest of your classes, there will be no essays used in examination, tests will only ever be in the form of questions and practical examinations, both of which will go to separate marks in your final results.

"I'm not going to lie to you, Soul magic is the most advanced kind of magic that mortals have ever come in contact with, and not everyone here is going to be capable of using it, in fact, I predict that only 20% of you will, and NO, a mortal's ability to use soul magic is  _not_  effected by whether they are a monster or a human, can anyone guess why?" Falmercia scanned and saw a single hand raised, and nodded in their direction.

It was an old lady with glasses that answered, "Would that be because soul magic is the natural magic of demons, similar to how DETERMINATION is the natural 'magic' of humans, and as a consequence both humans and monsters are equally disadvantaged?"

Falmercia nodded, glad that she didn't have to teach everyone in this room from complete scratch, "That's correct, soul magic  _is_  the natural magic of demons. You mortals will never be as  _skilled_  at soul magic as a demon will be, because we are all created with a complete understanding of the art. Although, there is a rare case where you might be able to overpower a demon with soul magic, however, I will get back to that later on."

Falmercia caught Sans raising a non-existent eyebrow at her, but she chose to ignore it. "One last thing before I move on to regular content; they call me a sloth demon for a reason, it's already too much effort for me to tell you once, so listen carefully, because I'm not going to repeat myself. And make friends with your fellow students, because they're the only ones that will save you if you miss a lesson."


	2. Chapter 2

**Summary for the Chapter:**

> Falmercia spills a few beans on demons, Sans and Frisk are still dealing with their sloth stained souls.

"you know, you are such a lazy teacher, it's  _sinful_ ," Sans said making Papyrus groan. Sans, Papyrus and Frisk were visiting Falmercia in her room. The room still didn't have any lights; however, everyone had long since gotten used to the lighting issue.

Falmercia shrugged, leaning back against the headboard of her be as she sat on it, "Soul magic's a big topic, and because you losers don't even know the bare basics, I have to teach you from scratch, and I don't want to have to split topics between classes, then I'd have to remember where I was up too, which would just be too much effort.

"BUT FALMERCIA, TO NOT TEACH ANYONE  _ANYTHING_  AND SPEND HALF THE LESSON SLEEPING IS A BIT TOO FAR, DON'T YOU THINK?" said Papyrus.

"i wouldn't say she didn't teach us  _anything_ ," Sans defended Falmercia, "i did learn something new before she decided to put the lesson to  _rest_." Sans looked directly at Falmercia, "you said demons were  _created_ , created by who?" Falmercia had been consistently tight-lipped on the subject of demons, and Sans had a feeling that they needed to know more. What gave him this feeling? He didn't know.

Falmercia blinked, "Who else? The Devil." She said like it was obvious. Everyone else in the room stilled coming to a sudden realisation that they should have probably come to before.

"So, you are saying…" Frisk started to ask in a quiet voice, "That God and the Devil are real?"

"Don't say that name! Do you want to kill me?! And of course, they're real." Falmercia snapped at Frisk, making them flinch back.

"BUT FALMERCIA, YOU SAID THAT NAME?" Papyrus protested in confusion.

"i thinks she's talking about the other one, bro," Sans explained, he looked to Falmercia, who confirmed his theory with a nod.

"BUT… WHY?" Papyrus asked.

Falmercia remained irritated, Sans had noticed that Falmercia was still not used to handling her emotions, even after all this time, but still, she managed to explain without shouting.

"We demons don't have an afterlife to go to, so we don't have to follow any of,  _His_ , rules, with one and only one exception. Do. Not. Commit. Blasphemy. It's begging for unwanted attention." Falmercia started sending glances towards the ceiling, as if afraid that lightning would strike through the roof and kill her where she stood.

"Sorry." Frisk apologised.

Sans was still in shock, as a scientist, this was a bit more difficult for him to handle, "i'm still adjusting to the fact that they're real."

Falmercia rolled her eyes, "Get used to it. If it makes you feel better, you mortals don't have exactly what I'd call an accurate record of either of them, what you lot know is at least 20% fairy tales and 15% demon propaganda."

Sans nodded. "So,  _why_  are demons created again?"

Falmercia shrugged, "Satin never told  _me_. To create mischief as possible, I think. We're created in groups -kinships- of seven. You know, one for each of the deadly sins. And kinships wok really well together too, we each have a role; sloth demons like me are the strategists, wrath demons are the main fighters, pride demons are good leaders, greed is a great motivator, gluttony demons see opportunities the others don't, envy demons are good at recognisance, and lust demons are great manipulators, the people demons."

Sans raised an eyebrow, " _You're_  a great manipulator."

Falmercia waved it off, "It's easy to convince someone to make a deal for something they already want. All demons sense mortals' desires, lust demons  _manipulate_  them. I've seen lust demons convince kings to give away their kingdom, mothers sell their children and turn bothers in arms to arch-enemies in less than an hour."

Frisk's eye sockets widened with interest, and Sans understood why. Again, Falmercia never talked about herself, and  _never ever_  about other demons, besides that they could use soul magic that was.

"What were  _your_  siblings like?" Frisk asked excitedly.

"Papyrus, you said you wanted to play a game of Trivia?" Falmercia changed the subject.

"BUT FALMERCIA, FRISK'S QUESTION." Papyrus protested.

"Papyrus."

"… ALRIGHT THEN."

* * *

Falmercia always won trivia, although Frisk knew that Papyrus tried very hard. It wasn't fair! Falmercia was trapped in the void for the last know knows how many thousands of years, yet she still always seemed to know the answer.

Frisk could have sworn that the demon of cheating  _was_  cheating, but demons couldn't lie, and Falmercia claimed she wasn't.

That was why when Falmercia pushed the game of Trivia to avoid answering Frisk's question, Frisk and Sans passed. With those two duking it out, they didn't stand a chance.

Instead, Sans took this time to test Frisk on her skills. It was because of school that Frisk hadn't been able to train frequently with Sans. She was always exhausted afterwards and on her weekends Chara and Asriel stole all of her time.

Speaking of the two of them, they had gone outside to watch and cheer her on. The two of them always seemed to be fighting for her attention, but despite this, there was still no doubt that they were best friends. No, this seemed to be more of a friendly competition, and Frisk didn't know how she felt about that.

First, Sans tested her on summoning regular bones, which was somehow her weakest point. While she could always conjure to bones, she sucked at control, her patterns were always wonky and this time a few of the bones even fell over.

Secondly, Sans tested her on her special 'attack'. Frisk felt a great sense of pride swell in her soul to know that her most powerful move was purely defensive, it felt her own magic was reassuring her that she was filled with love, not LOVE.

Sans was about to test her Gaster Blaster summoning when Frisk's legs collapsed under her.

"babybones!" Sans shortcut over to her, Chara and Asriel also rushed over her.

"I'm fine," Frisk reassured him, giving him a shaky thumbs up, all out of energy, "I'm just tired."

Sans frowned, "we're only getting worse." He closed his eye-sockets angrily before reopening them.

"that's it, i'm talking to her."

"Sans…" Frisk tried to stop him, but there was no stopping him. Sans grabbed her hand and shortcut back to Falmercia's room.

"falmercia, it's been a month since we got back to the surface. we've never had more rest before, but we're only getting  _more_  tired. there has to be a different way." Sans was using his serious voice, but Falmercia only laughed with amusement.

"To be honest myself, I'm disappointed that you still haven't figured it out. I mean, you've had a month of knowing me," Falmercia gloated, making Frisk frown. She didn't want a fight, verbal or not, but it was hard to avoid one when Falmercia kept making jabs at Sans.

"cut the crap, just tell us already," Sans growled. Frisk got even more nervous, Sans tried his best to avoid swearing in front of Papyrus and herself, so he must be furious now.

"No," Falmercia smirked playfully, "I already told you, you need to give in to the soul stain's compulsions"

"i just told you! in the past few weeks frisk an' i are getting more sleep than ever!" Sans shouted, and Frisk squeaked. Sans looked down at her guiltily, before taking a few deep breaths to calm himself down.

"As I have told you before because I'm a demon, I don't need to eat, drink, breath or sleep. Yet I sleep all the time because I want to." Falmercia said as if that would prompt an answer from them.

"I don't get it," Frisk said quickly before Sans could shout again. "We sleep whenever we feel the urge to."

Falmercia groaned, "I give up, it's too hard to make you figure it out yourselves. You sleep out of necessity, not  _sloth_ , because you're still confusing sloth for fatigue. It doesn't matter how long you sleep if all you do is try your hardest when you're awake."

That sort of made sense, sloth  _wasn't_  fatigue, but still, "But Sans was the laziest monster in the underground, and he was still affected by the sloth stain?"

Falmercia rolled her eyes, "The laziest monster who also had the most jobs in the underground, the effort just doesn't balance out."

Sans sighed, "so, what do you suggest?"

Falmercia shrugged, "For one thing, don't bother doing the homework I set in class, I won't bother checking it. Basically, don't do anything you don't  _have_  to do, that should be a  _start_."


	3. Chapter 3

**Summary for the Chapter:**

> Papyrus manages to convince Falmercia to leave the house and Falmercia explains the basics of soul magic.

The Great Papyrus was great at many things and as such, he had a long list of achievements. Judging from the others' reaction, one of his greatest achievements was befriending Falmercia so much that she would allow him into her room whenever he wanted.

But he could do one better. That's right, the Great Papyrus had managed to convince the sloth demon Falmercia to join him on his morning runs! Although he hadn't managed to get her to run herself, he had managed to work her up to just above a normal walking pace and he had slowed down to match her pace.

Certainly, no one else could do  _this_! And certainly, no one else could make her smile while doing exercise. That's right!  _Smile_ , genuinely smile. Not smirk! Not in a tease! SMILE!

They had been walking for a while in fact, four hours, as Papyrus had managed to get Falmercia to leave the house at 4 am, and as they were not running, he had needed to extend the time to meet his exercise quota.

How had the great Papyrus come up with this brilliant idea? Why, he remembered how Falmercia had told them that she didn't need to sleep! So, he figured that unlike the rest of his family and friends (Friends! He could now call Undyne his friend!), Falmercia didn't experience fatigue, and right he was! Even Undyne would have moved on and left an hour ago (less out of fatigue, and more out of boredom), but Falmercia refused to let herself get too far away from Papyrus.

In all honesty, Papyrus didn't understand why the others struggled so badly when it came to Falmercia, it was like they didn't realise that their presence made her on edge.

Sans  _had_  said that he thought that Falmercia had paranoia and Papyrus… had to agree. Even now Falmercia was watching her surroundings so very carefully. So maybe it was that the great Papyrus was the only one who Falmercia trusted.

Falmercia suddenly stopped in her tracks and her shoulders hunched slightly. Her eyes had stopped moving and were now pointedly staring at something. Papyrus also stopped for his friend.

"FALMERCIA, WHY DID YOU STOP?" As he asked her, concern started to pool in his soul.

"Someone's watching us." She said, refusing to move her eyes. Papyrus tried to see what or who she was looking at, but couldn't tell as it was a crowded area.

Papyrus tried to shake her worries. Why would anyone be watching them? This  _had_  to be paranoia. "ARE YOU SURE?... MY BROTHER SANS SAID THAT YOU MIGHT HAVE PARANOIA, IT IS A HORRIBLE MENTAL DISEASE AND IT WOULDN'T BE YOUR FA-"

The shaking of Falmercia's head cut him off, "I am absolutely certain." There was no doubt in her voice, and Papyrus actually believed her this time. "We need to get out of sight, let's duck down that ally way and head directly home."

Falmercia pointed to an alleyway directly to their left without looking, Papyrus thought it was a good plan, but Papyrus found himself hesitating. "SANS SAID IT WASN'T SAFE TO GO DOWN ALLY WAYS ON THE SURFACE WORLD."

M q

"You don't need to worry about that when you and I are together, there isn't a threat that is capable of defeating us," Falmercia said it as if she had already thought of it before, and planned it out in detail.

"THEN WHY ARE YOU AFRAID?" Papyrus asked.

"It isn't an attack I'm scared of, come on." Falmercia tilted her head back to the ally way. Papyrus hesitated again, but went in, Falmercia waited until he was a few steps in before she followed.

In the alleyway, there was a man, he was leaning against a wall smoking a cigarette. After taking a single glance at Papyrus and Falmercia, he scowled. Papyrus recognised that look, this man was a monster hater. It seemed though that he wasn't violent.

Suddenly there was a change in the man's demeanour and he threw down his cigarette and started to walk angrily towards Papyrus.

"Hey, freaks! What do you think that you are doing in  _my_  ally way! Go back to where you came from! Die you demons!" The angry man only seemed to get angrier, he picked up a broken piece of metal pipe and raised it to strike Papyrus.

The metal pipe was in front of Papyrus in a split second and the pipe collided in her face harmlessly. Papyrus vaguely remembered something that Chara once told him; attacks made with bad intentions cannot harm demons.

Papyrus could only watch as Falmercia swiftly summoned her staff and pinned the man to the wall.

"I'm sorry," She said, face inches away from the man's face as he struggled against the pipe with all of his strength. Papyrus knew that the man had no chance, not when Falmercia had super strength. "It's just you attack the wrong one, you said 'die you demons', and  _I'm_  the demon, Papyrus is just a mortal, just. Like. You."

Papyrus saw Falmercia put more pressure against the man, he stepped forward. "FALMERCIA, I THINK YOU SHOULD STOP NOW." He asked concerned for the man's life, but she didn't listen.

"But of course, you didn't really mean 'demon' did you, you just meant monster, but because you can't tell the difference you said demon. Well, I'm going to teach you now, I could kill you if I wanted right now, and never feel any guilt at all, while precious Papyrus here, a monster still feels bad for accidentally tripped Chara three weeks ago." Falmercia's voice was cruel, the only time Papyrus had heard her talk like this was back in the underground.

She was right, he  _did_  still feel bad, but wait- "FALMERCIA PLEASE STOP!"

"And would you look at that, despite how you just attacked him, a monster just saved your life, I'd be grateful if I were you." Falmercia released the man, and she must have activated her aura because he slumped to the ground asleep.

"Papyrus, we have to be quick,  _they're_  still watching, so how about we run?"

—

Sans watch Falmercia carefully as she walked to the front of the classroom. His brother had told him about the incident this morning in great detail, and it had both answered and raised a lot of questions.

It wasn't the attack in the alleyway that had caught his attention.

For one thing, he didn't think Falmercia had paranoia anymore. She did have someone that was watching her. Sans didn't understand what Falmercia had meant when she had said that Papyrus and her were some kind of dream team, but the identity of her stalker probably had something to do with it.

He just wished that Falmercia would TALK about it.

"Okay class, a quick history lesson to kick the lesson off," Falmercia said, cutting off his train of thought.

"For thousands of years, mortals have had small tiny glimpses into soul magic, there are even notable examples of them having advanced soul magic techniques; the greatest of all would be the barrier that trapped the monsters underground for centuries. However, mortals have failed to pass this knowledge down as they didn't have the resources to teach it." Sans figured that made sense, and he saw that his dad had already started to make notes, however, he was following Falmercia's very own instructions and didn't bother to get out his book.

"Mortals, of course, gained this knowledge from demons through deals or more formally known as contracts. In the demon community, these demons were looked down upon as these were very stupid deals to make. Why teach a man to fish when you would earn a lot more to sell him fish every day? I'm already hated so this couldn't possibly make anything worse." The class laughed, but Sans thought about it. She was hated in the demon community… that could mean something.

"There is one demon that has been famously been despised as he taught mortals the one school of soul magic that was basic enough for them to pass on. Healing magic." Falmercia paused to let the class absorb that in. Gaster turned over to a whole new page and started writing like crazy. Sans himself was having a hard time.

Healing magic was a branch of soul magic? But that was extremely common! Both Gaster and Papyrus already knew it!

"Okay class, who here knows how to use healing magic?" Falmercia asked, and Gaster put his hand up, as well as half the monsters and a few of the humans.

"Congrats! You have an automatic advantage in the rest of this class, on a side note, keep your hand up if your soul trait is kindness green?" Gaster was the only one to put his hand down. It was an uncommonly known fact that monsters also had soul traits, however, their soul' trait's colour wasn't visible in their soul.

"Take notes on this! Certain soul traits also have an affinity for soul magic, this is because soul magic requires both power and concentration to use, and certain soul traits are better at harnessing both. It is easy to be both filled with kindness and focused, but it is not as easy to be filled with bravery and focused." Sans nodded and stored that info for later.

"Because of this, green kindness souls are the most common souls able to use soul magic effectively, though purple perseverance is also pretty close to it. Though there is a soul trait that can wield soul magic even greater than kindness, can anyone guess it?"

Nuh ah, there was no way.

"Red DETERMINATION." Gaster guessed it, and Falmercia nodded, Sans felt his energy drain at the thought.

"That's right, red DETERMINATION, there are multiple reasons why it's so rare. Red DETERMINATION souls are the only souls capable of wielding soul magic with more power than black demon souls." That thought was oddly disturbing in its own way, as Chara was the only one with a DETERMINATION soul left that Sans knew since Frisk's soul had shifted to kindness since monster souls couldn't be DETERMINATION.

"What else can you hypothesise about soul magic from your knowledge about healing magic?" Falmercia asked.

A girl answered, "You can only use it on others with direct contact with their soul?"

"That's correct!" Falmercia confirmed.

"Wait," For the first time, Sans spoke up in class, "I have seen you use soul magic before without contact."

Falmercia nodded, "That's right, I was using it under contract magic, which allows the user to break the distance limits of their magic. Oh, and would you look at the time, class dismissed."


	4. Chapter 4

**Summary for the Chapter:**

> Confrontation.

Chara and Asriel had been sent out by their mother to get some groceries for tonight's party. It had been discovered on very short notice that it was, in fact, Gaster's birthday today so their mother had declared that they needed to organise an emergency surprise party.

Chara though had felt odd since they left the house, and she could tell Asriel was suffering from the same issue. They felt threatened.

That was disturbing, but for a different reason than what was to be expected. They both had retained their LOVE from their time in the underground; the only threat to them now was Falmercia, and for Chara humans, but even most humans didn't stand a chance against her, not with her level of experience.

But threatened they felt, and they knew for a fact that Falmercia wouldn't waste any effort following them.

They tried to brush off their discomfort with light chatter, their conversation switched over to Frisk.

"Isn't it obvious, Frisk is obviously closer to me! She shared her lunch with me when I accidentally left it at home yesterday," Asriel argued.

"Nope, they like me more because I help them with their homework, you see, unlike you,  _I_  help her, rather than the other way around."

It was an ongoing competition between the two of them, whoever became Frisk's friend had obviously been forgiven the most. Chara had started with a disadvantage because Frisk had been utterly terrified of them, but they had worked hard and now the two were neck-and-neck in the competition.

Chara  _would_  win.

They were walking back home when Chara felt a sudden chill go up their spine, they grabbed Asriel's hand and stopped in their tracks.

"Chara?" Asriel said in confusion.

A man with grey skin stepped out from the shadows to their left and glared at them with black eyes. Chara felt themselves grow angry without reason.

"Perceptive, but still, it's hard to believe that she'd replace us with  _you_." The man said.

"I don't know what you're talking about," Chara replied, but the man continued as if she hadn't said anything.

"Though I guess you aren't her favourites, maybe the others are more impressive." The man took a few steps closer and Chara reached for their knife that was hidden in their shirt.

The man grabbed her arm in an instant, "As much as I admire your wrath, I  _really_  wouldn't." Chara felt themselves freeze in fear. "The name's Vindic, remember it, I want you to tell Falmercia that we met, but keep quiet about it 'till tonight, alright. If you don't, the goat will die."

Vindic let go of Chara's arm. As soon as Chara blinked, he was gone.

They shared a glance with Asriel. It wouldn't hurt to wait until tonight, right?

* * *

"No, I'm not going to some stupid party, they're exhausting." Falmercia refused.

"Come on," Frisk insisted, bouncing enthusiastically, "It'll be fun!"

Falmercia shook her head. Sans had been watching the scene in front of him so far with endearment. Frisk was truly adorable when she got this excited.

"it would mean a lot to everyone if you showed up." Sans decided to help her out, "you could use a chance to show them that you aren't as bad as undyne thinks."

Falmercia rolled her eyes, "So, do you really think I care about what they think?"

Frisk playfully punched Falmercia's shoulder, "Yeah! I mean, if you didn't you wouldn't have agreed to go walking with Papy!"

Falmercia didn't respond, she was instead staring in horror at her health bar, which had lost a whole quarter of health.

"Falmercia… I gosh, I'm so sorry!" Frisk apologised when she saw what happened, and Sans watched in concern for Falmercia's reaction, thinking just one thing; did frisk just ruin their treaty?

Falmercia nervously chuckled, "Heh, don't worry about it kid, if you meant it, you wouldn't have been able to deal the damage. So that party; fine, I'll go, but I'm only staying as long as Papyrus is."

Sans chuckled nervously.

* * *

Chara shifted their weight guiltily from one foot to the other as they watched through the window as Falmercia walked to the front door and they heard the sound of the doorbell.

The party was at the skeleton family's house, and they had gotten there earlier as their mother was preparing the food. Chara pondered absentmindedly why Falmercia had not short-cut here and why she insisted on walking everywhere.

"I thought that Papyrus would be here," Falmercia said, Chara could hear a slight nervousness in Falmercia's voice. Guilt pounding in their chest, Chara looked out the window and to the sky. The sun was setting slowly, so she figured it could do no harm to wait another hour before they told her about before.

"paps is out distracting gaster while we set up for the party, he'll be here in an hour, so you'll have to just tolerate us until then," Sans explained to Falmercia.

Chara walked around to see that Falmercia was frowning. Chara inwardly chuckled, Falmercia really did look uncomfortable when Papyrus wasn't around, the demon really must suck at communicating with people normally.

Frisk had that sympathetic look in her eyes again, and grabbed Falmercia's hand, "Don't worry! It won't be  _so_  bad, you and I can prank some people until he gets here!?

Asriel burst out from the neighbouring room, "Yeah! That sounds like fun! I wanna get back at Undyne for bench-pressing me in front of everyone!"

Chara stepped out for everyone to see, "If it's mischief you're up to, you can't leave me out of it."

It was best they stay close to Falmercia.

* * *

Sans knew he had a bad feeling when the three kids offered to go pranking with Falmercia. While he, himself enjoyed pulling a good prank or two or three or four… He knew the four of them working together could create one  _monster_  of a prank.

He  _really_  wished he had been wrong though. Because as the sun was going down, he had to be the one that stood between Undyne and Falmercia.

Falmercia was just smirking at Undyne's rage-filled, egg-covered feathery, sparkled face. They had gone along with Asriel's idea of pranking Undyne, and with Falmercia's help, it had been one  _hell_  of a prank.

Falmercia had enchanted one of Frisk's smaller bone shields to dissipate when it got close to Undyne's soul and then repurposed it to carry a bucket that Chara and Asriel had filled with eggs, feathers and glitter. When Undyne went outside to help with the backyard to help with the final decorations, the bucket had landed right on her head.

Asriel and Frisk, being good kids, had taken responsibility, but Falmercia's involvement complicated things. Anyone else would have gotten off with a head noogie, but since Undyne had a reasonable grudge against Falmercia, she was out for the demon's blood.

"if you hit her, i'm not going to help you when she retaliates," Sans warned.

"Get out of the way Sans! I need to teach that THING a lesson!" Undyne growled, and Falmercia chuckled in response.

"U-u-undyne, y-you know th-that you w-won't be able to do any d-damage when you're angry like this." Alphys tried to reason with Undyne, and Falmercia's chuckle turned to full blown laughter.

"SHUT UP!" Undyne shouted.

"Undyne, really, the prank was my idea," Asriel tried to redirect Undyne's anger again, "Falmercia just played along with us."

Undyne was about to respond when Falmercia's laugh suddenly cut off and she turned around to face the growing line of shadows in the backyard.

"Everyone get behind me and don't do anything stupid." Falmercia's voice was dead serious, and it seemed that even Undyne could hear the nervousness in her voice because she calmed down enough to grab Asriel and Frisk and put them behind her.

Falmercia's eyes did not leave the shadows, "I know you're there Vindic!" She called into the shadows, "Come on out! All of you!"

A man walked out from the shadows, and Sans could instantly tell that he was a demon from his grey skin and black eyes. He was dressed a lot differently than Falmercia's business attire. He had a fluoro pink Mohawk and wore a black shirt with a silver skull and short blue jeans, though the most absurd part of his attire was his fluoro pink boots. Again, following the theme of fluoro pink he had two tattoos, one on his right shoulder, which Sans recognised as the devil's symbol and on his left forearm an anarchy symbol.

"Well done sister, observant as always, even with the red-eyed brat keeping their promise." Vindic directed his gaze at Chara, "And for that, I'll keep my promise and I won't kill the goat.

"The others too," Falmercia glared back to the shadows. A female demon walked out of the shadows, she had long, green hair, heavy make-up and wore a ball gown.

"Well, you lot obviously by now know that my brother here is Vindic, the ever-famous Wrath demon of vengeance, while I'm only, Indigo, the Envy demon of the family." The demon took a glance over everyone with a frown, "So she left us for  _you lot_ , I was expecting… better." She taunted.

Yet another demon revealed themselves, stepping forward, this one had white hair, hipster-glasses and wore a black trench coat with a purple scarf, "Well, her favourite isn't here yet, so it is possible that he is better," He reasoned, raising his hand to adjust his glasses.

"Don't act like that wasn't on purpose Wisac, we all know you wouldn't dare come here if he was," Falmercia retorted, "not that I blame you, instincts and all."

Falmercia tilted her head from side-to-side looking into the shadows, "Where's Aropoph, Megalo and Frudole? Couldn't they make it?"

"Frudole's dead!" Vindic snapped, and Falmercia flinched, summoning her staff.

"And Aropoph and Megalo are keeping watch, as you said, we don't want to be here when your favourite arrives," Wisac said in a studious tone.

Falmercia looked down for a moment, a shadow hiding her face, before she looked up with a mad grin on her face, "So, what you are saying, is that you are without your strategist AND your manipulator, no wonder you are low on souls."

And that is when Sans realised how weak these demon's auras were. While he felt a vague manipulation, they paled in comparison to even Falmercia's weakest aura from when she just escaped the void.

Vindic grew a sadistic smile, "Yes, your betrayal hit us pretty badly, we've been in poor business, even with our star players." The chill in his voice made Sans hear the obvious threat. "Did you really think that you could hide from us forever? Well too bad, because now that we've found you, we are going to make you suffer… and then we are going to kill you."

Undyne growled, seemingly having enough of listening to the showdown and made a charge at Vindic.

"Idiot!" Falmercia cried as Vindic summoned a black bow and shot Undyne in the chest, causing her to fall in her path. Vindic waved his hand to summon another arrow and pulled the string to aim again when he and the other two suddenly turned their heads.

Vindic chuckled, "You're lucky, fish." Before they retreated into the shadows.


	5. Chapter 5

**Summary for the Chapter:**

> Necessary Exposition. 
> 
>  
> 
> I'm sorry.

"Inside, now!" Falmercia shouted, pointing at the door.

Sans' eye-lights were fixated on Falmercia's face, while it was understandable, her behaviour was completely unlike her. He had assumed that she would at least try to seem cool, calm and collected as usual, but she was pacing and she had the vibe of a ticking time bomb that would go any moment.

He didn't even acknowledge Papyrus when he entered the room with Gaster.

"FRIENDS, WHAT IS GOING ON? YOU WERE SUPPOSED TO SAY 'SURPRISE'." Papyrus said innocently.

Falmercia turned to face Papyrus, "Sorry, the party's ruined and that's all on me, I take full responsibility," She spoke fast, frustration showing in her voice.

"ARE WE JUST GOING TO STAND HERE AND DO NOTHING?" Undyne shouted, when Falmercia didn't respond, she huffed, "THAT'S IT, I'M GOING AFTER THEM!"

Falmercia suddenly turned to Undyne, "No, don't-!" But she was too late Undyne already left out the back door. "Dammit!" Falmercia let out a frustrated scream and punched her arm through the wall.

Papyrus approached Falmercia with a gentle look in his eye-sockets, "DEMON-"

"Don't call me that!" Falmercia snapped directing her anger at Papyrus. Sans felt himself take a protective step closer. "That's what  _they_  are, and, and, I'm not like them, not anymore! They don't  _care_  about anyone!"

Papyrus put his hands on Falmercia's shoulders, "FALMERCIA, YOU'RE SHAKING."

Sans blinked. How had he not noticed that? That was when he realised that Falmercia wasn't angry, she was  _scared_. More scared than he'd ever seen her before.

Falmercia's mouth trembled as she answered, "You would be too if you knew what we're up against."

Papyrus didn't seem phased, "THEN PERHAPS DE-FALMERCIA, YOU SHOULD  _TELL_  US." How could his brother be so understanding when he knew the least about what was going on?

Sans smirked. His brother was  _so cool_.

Sans turned his gaze, to Chara "but first, perhaps we should ask the brat here what vindic meant earlier. you knew he was up to something! why didn't you tell us?!" Sans shouted, and Toriel sent him a glare.

Chara looked down guiltily, "Asriel and I bumped into him on the way home… He said that if we told anyone, he'd kill Azzy."

Sans fumed, "you-"

Falmercia cut him off, "For once, the brat did the right thing." Sans turned to her in shock. Falmercia didn't exactly hide how much she hated Chara in the past, and now she was defending them? What was the world coming to? "He may not have struck a deal, but Vindic's an idiot. Demons can't lie and he said he wouldn't kill Asriel. So at least he won't kill Asriel, sure, any of the others can, but with the possible exception of Aropoph, they're all likely to be quick about it unlike him."

Sans looked back to Falmercia, still sour and feeling the need to place some blame, "And why exactly would the want to kill him in the first place?!"

Falmercia was silent for a moment.

"They must have noticed that my chain's broken. I know because they said  _suffer_ , then die. Demons don't have an afterlife, so dying  _is_  suffering." She said like that was an explanation.

"and what does that have to do with wanting to kill asriel?" Sans questioned.

Falmercia was having a really difficult time answering, "They must have sensed the contract between us. They want to make me suffer before they kill me. So, they're going to get to me, using you guys."

Sans… couldn't force himself to get angry at that. That implied… She  _cared_  about them? Since when?... Sans sighed. What was he thinking, of course he knew? Really, it should have been obvious from the way how she humoured Papyrus in his jogs and assisted the kids in their mischief. Not something someone so lazy would do if they didn't care.

Falmercia's soul for the first time ever could feel love rather than LOVE. And of course, her fellow demons would use that against her in this… revenge?... whatever this was.

Falmercia sighed, "Well, Papy's right, I'm just going to have to tell you." She looked up to Gaster, "Sorry, your Party's going to be completely ruined after this." She said in dry humour.

Gaster shook his head, "Learning about demons? That would be quite the birthday present."

Falmercia chuckled, before becoming serious again, "Alright, we're up against five demons. These demons were my kinship back before I got tired of world domination. They turned out to be useless without me and my sixth sibling, Frudole, the lust demon of the kinship, died.

"The remaining five are of course; The wrath demon Vindic, sin of vengeance, pride demon Wisac, sin of know-it-all-ism, envy demon Indigno, sin of unworthy reward, greed demon Megalo, sin of megalomania" Sans sent a glance at Chara, who looked down. "and my least favourite, gluttony demon Aropoph, sin of cannibalism."

Everyone in the room shuddered, Falmercia smiled dryly, "But don't you lot worry, you're not demons, so you're not on the menu, but I happen to be at the top."

Sans was already beginning to understand why Falmercia was so terrified.

"They might not have any souls with 'em, but all demons have a basic skill set. We all have aura's that compel mortals to fall to our deadly sin. We all have advanced soul checks. We all have varying increased strength and speed, by the way, for reference, I'm the weakest and slowest. We all are experts at soul magic and we all can form contracts." Falmercia continued to talk for a while, but everyone else remained dead silent, nobody wanted to miss a thing she said.

"We each can summon different weapons, suited to make things more difficult for us in battle. I summon a staff because I'm a sloth demon and it requires more effort to defeat someone with a staff compared to skill based tools. Vindic has a bow because he can't put passion or rage behind it like other weapons. Wisac will have a knife, a coward's tool that has blood cover him and damage his pride. Indigno will have a long sword because she will want everyone else's weapons anyway. Megalo doesn't get anything but has a special skill of being able to kill other demons with his claws. And Aropoph has the ability to eat anything so she never needed a weapon in the first place."

Gaster raised a hand and stopped Falmercia in her explanation, "Why wouldn't they just use mortal weapons?"

Falmercia answered, "Demon weapons are infused with hate, so half the damage they deal is unable to be healed with soul magic. Basically, if demons used regular weapons in demon battles we'd just keep being able to self-heal and we'd get nowhere."

Sans raised an eyebrow, "wait, chara said that demons can't be hurt by bad intentions,"

Falmercia nodded, "That's true for mortals, all demons are equally the evillest things imaginable, so the intent cancels out." Sans pondered that for a moment. He had a theory, but he couldn't voice it yet. He didn't have proof and he couldn't bear to bring the others' hopes up.

"A final skill that all demons possess is called the '100 rule'; if a demon collects 100 souls they gain 'true immortality' for 100 days before losing the 100 souls. A demon with true immortality gains infinite Hp and simply, cannot die." When Falmercia said this, she had a look in her eye, a 'planning look', and Sans wasn't sure he like it.

Falmercia continued her explanation, "And then we each have our own skills, mines enhanced intelligence; pretty much what it sounds like, I have an IQ of 300, an eidetic memory, and an enhanced desire check. While all demons can sense a mortal's desires, I get a better read on  _why_  they want something."

Sans could only find a mild comfort in knowing that he was outsmarted by the smartest of the demons he had met.

Falmercia frowned, "Vindic's abilities are mostly simple, he's stronger and faster, but because he is also the sin of vengeance, he knows how to make anyone hurt. I already told you Megalo's and Aropoph's abilities. Indigno can copycat anything she observes, in person, I should add, not that it matters so much with our lifespans. Wisac has boundless confidence, a slightly stronger aura but…" Falmercia hesitated, "Like Vindic he also has a specialised skill because his sin is so common. He can make you 100% certain in something that you already know. It sounds weird but… if you were only suspicious that your friend lied to you, he could make you certain, and unable to be persuaded otherwise, even with proof."

That… that didn't sound good. Sans shuddered when he remembered how Undyne ran off earlier.

"So, idiots, I have a plan!" Falmercia said confidently. Sans sighed in relief, finally, some good news.

"You lot are all going to pack your bags and go back and live in Alphys' old lab. The radiation from the CORE will prevent them from being able to 'short-cut' in and I can set up some basic barrier to prevent them from getting in. They aren't going to want to go anywhere near Papyrus, so he and Sans will go out and get supplies when you run out. Other than that, none of you are to leave. Meanwhile, I'll go out on my own to go for the '100 rule' and take care of things."

Everyone shouted protests at once, but Toriel's was by far the loudest of the bunch.

"There's no way I'm letting you kill a hundred innocents!"

Falmercia rolled her eyes, "I wouldn't be killing them, I'd just be making deals. There are easily a hundred humans that would sell their souls to become monsters now that they know that they're real and can do magic."

Toriel fumed, "You will still give them stained souls, do you know no shame?"

"no, she doesn't" Sans answered for Falmercia. He was angry about Falmercia's plan like the rest, but he couldn't place it completely on her. "she has this magical chain strapped around her soul that seals away her conscience. she can probably tell the difference between right or wrong but she simply cannot care."

Toriel blinked and turned back to Falmercia, whose silence only confirmed what Sans was saying.

"PLEASE FALMERCIA," Papyrus spoke up, "I KNOW THAT YOU WILL NOT FEEL BAD IF YOU CAUSE ALL THOSE PEOPLE PAIN, BUT I WILL KNOWING THAT YOU DID IT FOR OUR SAKE."

Falmercia looked at Papyrus with pain in her eyes, "The only other way puts all of you in danger." She pleaded.

"I DON'T CARE. PLEASE."

Sans had to admit, thinking about it, Falmercia's plan would have kept them all safe while putting herself at great risk, while having them with her would have kept her safer. He had to feel a small bit of respect for her DETERMINATION to keep Papyrus safe.

Falmercia closed her eyes, "Fine, we'll do it your way Paps."


	6. Chapter 6

**Summary for the Chapter:**

> Sorry, this took so long! School has been the _devil_.

Asriel wasn't exactly sure what he thought about Falmercia. As Flowey he had seen her as a threat, but now that he had a soul again, it was becoming harder to see her objectively. True, she was still terrifying in a 'she could kill his entire family without trying too hard', but she also had been pretty nice. Also, the fact that she was stressing the way she was right now was a bit of a sign to him that she actually cared about everyone.

She had even given up something that he had never thought the sloth demon would - sleep. They had all been moved to the lab on the surface to stop one of those demons from taking them out individually - everyone was taking off time from work and school even - and everyone had been discussing taking turns to stay up and keep watch. Asriel was surprised by how against the idea of staying up that he was, with his first soul having full permission to stay up all night would have been the dream, but now…. Now he was just too tired to.

Falmercia came to his rescue (and Sans and Frisk's he realized) and said that she didn't trust any of 'the mortals' to stay up, and demanded that she be put in charge of it since demons didn't actually need to sleep. It was odd, Falmercia had mentioned it before many times, but Asriel hard time remembering that fact considering how much Falmercia slept. Turns out the others, especially his mom had too, and Falmercia had to ensure them that she slept all the time more out of true laziness rather than having a sloth stained soul like he or Sans or Frisk.

While the grown-ups were moving stuff and Chara had stolen Frisk away to stars know where Asriel caught Falmercia mumbling to herself.

"Alright, if you're so eager…" Falmercia raised her hand and an orange soul flashed in front of her before shifting into what could only be described as a thinner, less visible form of The Barrier that used to trap them underground.

"What?" Asriel asked, what had Falmercia meant by 'eager'?

Falmercia looked over to Asriel, "I'm creating a miniature barrier with one of the souls, of course it's not going to mean much in the way of protection since a barrier of one soul only needs one soul to break, but anything it will act as an alarm bell to alert me if they try anything when I'm out."

"But won't that trap us in?" The lab was big, but being trapped would definitely make Asriel feel more claustrophobic than he was.

Falmercia smirked and shook her head, "Nope, I have built it so if you mortals want, you can come and go as you please, but only you lot, so if you have any unexpected guests for whatever reason you should send me a memo before someone dusts themselves."

"But how-?" That sounded way more complicated than the old barrier.

"Because I'm not a noob and actually know what I'm doing - I mean, it's basic soul magic."

It took a moment for Asriel to take in what Falmercia had just said, and he burst out laughing.

Falmercia sent him a questioning look.

"Hahaha… it's just… hahaha… noob…pffff!" Asriel got out between laughs.

"Contrary to popular belief, I actually pay attention when you kids talk about your games," Falmercia said snidely, although she was smirking in good nature.

She waved her hands in few oddly complex gestures, twisting and stretching the magic of the barrier. "That should do it. I'll be off now."

Asriel hadn't noticed Sans was standing right next to him until the skeleton spoke up. "off where?"

Falmercia looked back at Sans through the corner of her eye, "I'm going to scout out the playing field. A good tactician never sits idly and allows the pieces to move too long without interfering… even sloth demon tacticians."

Sans narrowed his eye sockets, "alright, if that's all you're planning on."

Falmercia left without saying another word. Why did Asriel not like this?

* * *

Papyrus cringed as he searched through the kitchen for ingredients. Noodles, noodles, ketchup, noodles, coffee, ugh- a have eaten spider doughnut, that was it, he was going to the grocery store to retrieve some acceptable ingredients.

And who better to come with him than his friend Falmercia, now where was she? "FALMERCIA?! FALMERCIA?! THE GREAT PAPYRUS IS GOING TO THE GROCERY STORE, AND REQUESTS THAT YOU CO-"

"she's gone paps, left over an hour ago," Sans said from a doorway.

"OH?! WHERE DID SHE GO?" Papyrus turned to Sans, who shrugged, much to Papyrus' dismay. "THEN I SUPPOSE THE GREAT PAPYRUS WILL HAVE TO GO BY HIMSELF." Papyrus turned to the front door to leave, but Sans shortcut in the way.

"no can do, bro. as falmercia said, it's too dangerous to go out alone." Sans cautioned.

"OH." Papyrus looked down in disappointment. Everyone had been lacking DETERMINATION since they had been visited by Falmercia's siblings, and he really had been hoping that he could cheer them all up by cooking for them, but if he couldn't get ingredients, then that plan was busted.

"i guess i will go with you. falmercia said we'd be going out for supplies in her first plan, so it should be fine." Sans words made Papyrus beam.

"THANKYOU BROTHER." Papyrus new that his brother had been thinking a lot about recent events, and that his brother was concerned about what Falmercia was planning, but Papyrus didn't think that there was anything to worry about.

And no! It wasn't because he was naive like some of the others thought he was, he had good reasons! Falmercia  _was_  getting better, he could see it. She even knew it herself- she had told him when she told him to stop calling her demon! He was certain that Falmercia wouldn't actually hurt an innocent like what Queen Toriel thought that she was going to.

When the brothers had finished their shopping and had begun to head back, Papyrus began to feel uncomfortable… something just wasn't right. From what he could tell, Sans also sensed something was off, Sans went to grab Papyrus, but he was interrupted by a human male who pushed him out of the way and kept walking towards Papyrus. Papyrus nervously stepped back, unsure of what to do.

"I'm sorry man, I just can't stop." The human sounded pained, and without looking at what they were doing, pulled out a knife and went to stab at Papyrus.

Out of seemingly nowhere, a black quarterstaff collided with the human's head, causing him to fall to the ground. The staff faded into black mist, and Falmercia stepped into view, frowning. She summoned her staff again in her hand and kept walking towards the human on the ground.

The human got up again, and when to make another jab at Papyrus, but their soul suddenly popped out of their chest and turned blue as Sans sent the human flying against a wall, effectively keeping them pinned.

"falmercia, what's going on?" Sans asked, but Falmercia ignored him.

"You made a deal, didn't you?!" She accused loudly, oh my, she looked angry. Papyrus was beginning to notice she wasn't good at holding her newfound temper.

"Y-yeah?" The human managed to squeak out.

"With who?" She demanded again, now standing right in front of the human, her staff raised.

"I-I don't know." The human said, voice desperate, "Please, I didn't want to hurt anyone, I just couldn't control my-"

Falmercia didn't wait for him to finish his sentence as she stabbed the human with her staff, his soul cracked as his eyes became lifeless and her crumbled to the ground. Falmercia's staff faded into mist as she turned away.

"We need to leave before anyone else gets here."

The two brothers stared at each other eye-sockets wide.

"FALMERCIA, HE DIDN'T MEAN IT, WHY DID YOU HAVE TO KILL HIM?" Papyrus asked, feeling his soul fill with disappointment. No, she didn't just do that, the man was innocent!

"He made a deal, he wouldn't have been able to stop until you were dead Paps." She explained yawning, "I just wish I could take the soul, but that would draw you guys too much attention."

Hurt began to fill Papyrus' chest, Falmercia didn't even care! He, he had believed in her, and she had been completely merciless.

"falmercia, tell me that there was no other way," Sans asked, voice dark. Falmercia hesitated in her steps, but remained silent. The rest of the way back, they walked in a heavy silence.


End file.
